Primeiros Passos com Java

O PetraDB fornece um driver JDBC 4 padrao, entao voce usa a API familiar java.sql — Connection, Statement, ResultSet, PreparedStatement.

Instalacao

Maven:

<dependency>
    <groupId>io.github.edadma</groupId>
    <artifactId>petradb-jdbc</artifactId>
    <version>1.5.0</version>
</dependency>

Gradle:

implementation 'io.github.edadma:petradb-jdbc:1.5.0'

O driver se registra automaticamente — nao e necessario Class.forName().

Execute sua primeira consulta

import java.sql.*;

public class Main {
    public static void main(String[] args) throws SQLException {
        Connection conn = DriverManager.getConnection("jdbc:petradb:memory");
        Statement stmt = conn.createStatement();

        stmt.executeUpdate("""
            CREATE TABLE users (
                id SERIAL PRIMARY KEY,
                name TEXT NOT NULL,
                email TEXT
            )
        """);

        stmt.executeUpdate("INSERT INTO users (name, email) VALUES ('Alice', 'alice@example.com')");
        stmt.executeUpdate("INSERT INTO users (name, email) VALUES ('Bob', 'bob@example.com')");

        ResultSet rs = stmt.executeQuery("SELECT id, name, email FROM users ORDER BY id");
        while (rs.next()) {
            System.out.printf("%d: %s <%s>%n",
                rs.getInt("id"),
                rs.getString("name"),
                rs.getString("email"));
        }

        rs.close();
        stmt.close();
        conn.close();
    }
}

Saida:

1: Alice <alice@example.com>
2: Bob <bob@example.com>

Armazenamento persistente

Para dados que sobrevivam a reinicializacoes, use uma URL de conexao de arquivo:

Connection conn = DriverManager.getConnection("jdbc:petradb:file:mydata.petra");

O arquivo e criado no primeiro uso. Extensoes suportadas:

Extensao	Tipo de armazenamento
.petra	Armazenamento persistente seguro contra falhas
.ptxt	Formato de texto legivel por humanos

Prepared statements

PreparedStatement ps = conn.prepareStatement(
    "SELECT * FROM users WHERE name = ? AND id > ?");
ps.setString(1, "Alice");
ps.setInt(2, 0);
ResultSet rs = ps.executeQuery();

Transacoes

conn.setAutoCommit(false);
try {
    stmt.executeUpdate("UPDATE accounts SET balance = balance - 100 WHERE id = 1");
    stmt.executeUpdate("UPDATE accounts SET balance = balance + 100 WHERE id = 2");
    conn.commit();
} catch (SQLException e) {
    conn.rollback();
}

Proximos passos

Veja a referencia JDBC para a API completa, incluindo operacoes em lote, metadados, mapeamento de tipos e conexoes com servidor.